Embodiments of this disclosure relate generally to radiation systems and methods. In particular, various embodiments of a gantry system and a particle therapy system comprising such gantry system are described.
Particle therapy systems for treating patients are known. In particle therapy, charged particles such as protons or heavy ions are used to irradiate a region of interest such as tumor. Because of the “Bragg peak” effect, charged particles release most of their energy around the area where they stop. Therefore, by controlling the energy of charged particles, healthy tissue or critical organs distal to the source of charged particles receives substantially no radiation and the healthy tissue proximal to the source receives a significantly reduced amount of radiation. Furthermore, by choosing the energy of charged particles for irradiating different “layers” or “depths” of the tumor volume, the radiation dose distribution can be tailored to the shape of the tumor in all three dimensions.
A particle therapy system comprises an accelerator for producing particle beams, a beam transport line for transporting particle beams, and a beam delivery system located in a treatment room. The beam delivery system comprises a beam delivery line supported by a gantry body, which may rotate about the patient to allow particle beams to aim at the tumor from various angles. Conventional rotating gantries for particle therapy systems comprise custom made ring gantries. While conventional ring gantries can provide 360 or more degrees of rotation angles, most of them are huge and considerably expensive to build. Ring gantries are also difficult to align and very often show axial movement during rotation. Further, conventional ring gantries define a very limited space around the isocenter for the patient and healthcare personnel.
Arm gantries for proton therapy systems are currently available. FIGS. 1A and 1B illustrate a conventional proton beam delivery system 1 comprising a gantry body 2 generally in an L-shape supporting a beam delivery line 3 and a series of magnets 4 for bending and focusing the beam. The gantry body 2, supported by a front support bearing 5 and a rear support bearing 6, operates to rotate the beam delivery line 3 about a horizontal axis 7, allowing particle beams to aim at the tumor from various angles, as shown by the rotating gantry body 2 in phantom lines. One of the drawbacks of the conventional proton beam delivery system design is that the rotation angle of the gantry body 2 is limited. Because the supporting structure 8 supporting the front bearings 5 is fixedly mounted to the floor and wall, the gantry body 2 cannot rotate in full 360°. The gantry rotation angle (theta, FIG. 1B) is below 360°, usually between 200 and 220°.